Poly(arylene sulfide sulfone)s are engineering thermoplastics of potential commercial interest for film, fiber, molding, and composite applications because of their high melting points and heat resistance.
General processes for the production of poly(arylene sulfide sulfone)s are known. Poly(arylene sulfide sulfone)s can be prepared by the reaction of a polyhaloaromatic sulfone, such as bis(p-chlorophenyl)sulfone, with an alkali metal sulfide in a polar organic solvent.
However a major disadvantage has been that the poly(arylene sulfide sulfone)s are of relatively low melt stability and are not very processable. Further, the cured or processed polymers are of poor quality in that they appear black, brittle, outgassed, and of carbonaceous texture.
Poly(arylene sulfide)s, even containing small amounts of sulfone linkages (disclosed in U.S. Pat. No. 4,426,479), do not have the processing problems associated with poly(acrylene sulfide sulfone)s that have predominantly sulfone linkages. Poly(arylene sulfide)s do not carbonize during processing since they are able to be processed at much lower temperatures than poly(arylene sulfide sulfones) but yet are not as heat resistant as poly(arylene sulfide sulfones).
It would be most desirable to produce melt stable poly(arylene sulfide sulfone)s of good polymer quality that are capable of being processed and cured. Melt stable poly(arylene sulfide sulfone)s would provide improved processability, color, texture, flexibility, and toughness. In addition, melt stable poly(arylene sulfide sulfone)s should be able to be slowly cured, to increase the molecular weight, without destroying the quality of the polymer
It is an object of our invention to provide a process for preparing melt stable poly(arylene sulfide sulfone)s. It is a further object of our invention to provide a process for preparing poly(arylene sulfide sulfone)s of good polymer quality. It is a further object of our invention to prepare poly(arylene sulfide sulfone)s of good polymer quality having a stable melt flow during processing.